Istanbul : Maria Sharapova swept past Sam Stosur 6-0, 6-3 at the WTA Championships on Friday to retain a small chance of finishing the year as the No. 1-ranked player.
But if Victoria Azarenka beats Li Na in the final match of the day, Azarenka will be assured of staying No. 1.
Agnieszka Radwanska became the third player to advance to the semifinals when she edged Sara Errani of Italy 6-7 (6), 7-5, 6-4 in a match that lasted 3 1/2 hours. The fourth-ranked Radwanska will play Serena Williams on Saturday.